By Tracy Gantz
It’s the call no racehorse owner wants to hear: “Your horse is lame, but darned if I know what the problem is.” Horses have an amazing ability to develop lamenesses that can mystify even the most experienced trainer. But a diagnostic tool called nuclear scanning can often pinpoint minor lameness problems before they become major ones.
Racehorses develop lamenesses for a variety of reasons: The concussion of legs hitting a racing surface at high speed, the natural remodeling of a young horse’s bones as he is growing, or even the proverbial “wrong step,” similar to when we twist an ankle. At a walk, we do no harm, but that same minor misstep by a racehorse in full gallop can do all kinds of damage.
When you hurt yourself, you can describe your symptoms to your doctor. A horse, however, must depend on its handlers to find the problem. If the animal is visibly lame in one leg and shows heat and swelling somewhere in the lower leg, a trainer or vet can usually find and take care of it easily. But when an injury occurs higher up a horse’s skeleton, especially in the shoulder or the pelvis, it may be impossible to detect with anything but a nuclear scan.
Nuclear scanning-also called nuclear scintigraphy-can catch problems earlier than X-rays. It can also find them in parts of the body that are difficult to X-ray.
“This tells you on a cellular basis what the body is trying to fix-what’s wrong with that horse,” said Dr. Sylvia Greenman, the Southern California veterinarian who oversees the Nuclear Imaging Facility at Santa Anita. “I can often see a hot spot on a nuke scan that can indicate a subtle fracture that I can’t see yet on X-ray. That tells me that the body is trying to fix something there.”
Before nuclear scanning, lameness cases would arise where a horse X-rayed clean. Owners and trainers then faced the tough decision of whether to try to train through the lameness or try to treat something that couldn’t be found.
“Many times these horses would train through these problems and we’d get horses that would break their shoulders or their tibias and have to be put down,” Greenman said.
Today, a trainer or vet can order a nuclear scan and find these minor problems before they become major ones. A horse can receive the proper treatment and avoid a potential catastrophic injury.
Trainer Jenine Sahadi firmly believes in the value of nuclear scanning.
“I use it religiously,” she said. “It’s a great precautionary tool. You can find something coming before it hits. I’ve had cases where I have prevented a major fracture by using the nuke scan-I know it.”
Sahadi cited the example of Spinelessjellyfish, two-time winner of the Khaled Stakes. As a two-year-old, he developed a lameness in his tibia (the long bone above the hock), which Sahadi found with a nuclear scan. “I stopped on him, gave him four months off, and I’ve never had a problem since,” the trainer said.
A nuclear scan works by using a gamma camera to take a photograph of a horse’s bone. It will show a “hot spot,” or an increased area of activity, where there is a problem (see photo). It does this because a horse’s body responds to bone damage by sending calcium and phosphorous to the site in order to repair it. With a nuclear scan, a radioactive technetium is bound to phosphorous and injected into the horse’s bloodstream. The phosphorous goes to the injured site, taking the technetium with it. Then the gamma camera picks up the technetium, and the veterinarian can see the precise location of the problem.
“You find these things in the very early cellular stages,” Greenman said. “We can advise the trainer to lay a horse up before that hot spot becomes a fracture.”
If the horse receives time off in the early stages of an injury, he can return to racing faster and avoid something more serious.
Greenman said that nuclear scans often find injuries in such long bones as the tibia in the hind end and the humerus (the shoulder). Caught early, these have a very good prognosis for a return to racing at the same level as before.
Sahadi said that while she has no scientific proof, she believes these long bones are so dense that a fracture begins on the inside of the bone, where an X-ray cannot see it.
Nuclear scans also help diagnose fractures of the pelvis.
“In the past, the only way to image a pelvis if you suspected a fracture was to put the horse under general anesthesia,” said Greenman. “You had to lay them over on their back to take an X-ray of the pelvis. If you suspected a pelvic fracture, that means you had to wake that thousand-pound horse up and expect him to stand on a broken pelvis.”
The gamma camera can be positioned around a standing horse, so the horse doesn’t have to lie down. The horse is sedated merely to keep him calm, but he doesn’t have to stress an injured site for the vet to obtain a diagnosis.
Because nuclear scanning requires use of a radioactive material, Greenman and her crew take many precautions, as required by the National Regulatory Commission. The radioactive material is of a very low dosage and will not harm horses or the people who run the equipment. However, horses are kept in the nuclear scan barn overnight so that when they are returned to their own barn they register well below the standards of radioactivity allowable in the general population.
NRC regulations require that the building where nuclear scanning equipment is used be lead-lined. Thus, the procedure cannot be made portable. The Dolly Green Research Foundation, which is affiliated with the Southern California Equine Foundation, funded Santa Anita’s Nuclear Imaging Facility. Dr. Rick Arthur was instrumental in establishing the Santa Anita center in 1993, and he serves as director of the facility. Greenman is the supervisory user veterinarian, and licensed registered vet technician Barbara Billett and Martin Frausto assist her.
Two other Southern California facilities, Alamo Pintado Equine Medical Center in Santa Ynez and San Luis Rey Equine Hospital in Bonsall, also have nuclear scanning capabilities, as does the University of California at Davis in Northern California.
The cost to scan a horse ranges from $300 to $900 at Santa Anita, depending on how many scans are taken. But the price can be well worth it if the scan prevents further injury.
“I’ve prevented splits up the cannon bone and many other injuries with nuclear scanning,” Sahadi said. “I am a big fan.”
Lameness in racehorses is an unfortunate fact of life. But with early diagnostic tools such as nuclear scanning, trainers and vets can minimize the trauma to your horse, keeping him happy and running well for you.